File Ex from std_stdio won't compile

[Paul]

I copied the code below from this site under the std.stdio 
library reference section and tried to compile it.  I downloaded 
D2/Phobos.  Compiler says "fileread.d(4): Error: undefined 
identifier File"

If I add import std.stdio to the beginning it get ; expected, 
function declaration w/o return type, etc.

Assistance is greatly appreciated.

  void main(string args[])
{
     auto f = File("test.txt", "w"); // open for writing
     f.write("Hello");
     if (args.length > 1)
     {
         auto g = f; // now g and f write to the same file
                     // internal reference count is 2
         g.write(", ", args[1]);
         // g exits scope, reference count decreases to 1
     }
     f.writeln("!");
     // f exits scope, reference count falls to zero,
     // underlying FILE* is closed.
}